Many active substances, for example pharmaceutically and nutraceutically active substances and food ingredients, are susceptible to oxidation on exposure to the air or to dissolved oxygen for instance in a humid or aqueous environment. For many, the oxidation process is induced by (ie, either initiated or accelerated by) exposure to UV radiation such as from natural daylight. Lipids such as oils tend to be particularly readily oxidised.
This susceptibility reduces the stability of the active substance and of any composition containing it. This can lead to reduced efficacy and/or to the generation of undesirable by-products which can for example spoil the flavour of a food product (eg, when fats and oils turn rancid), increase the toxicity of a drug formulation, compromise the appearance of a cosmetic product, cause operating problems for a fuel within an engine, or more generally impair performance during use.
Active substances can be protected from environmental influences such as oxygen and UV light by encapsulating them in suitable delivery vehicles. The preparation of such active-loaded delivery systems can often be complex, time consuming and expensive however. Problems can arise in ensuring that the encapsulating entities are sufficiently uniform in size and shape to ensure the resultant formulation meets quality control and regulatory standards and to provide homogeneity in active substance concentration. It can also be difficult to achieve adequately high active substance loadings in the encapsulating entities, without making those entities relatively large in size and in turn compromising the physical properties of the overall formulation.
It is moreover necessary to ensure that any encapsulated substances can be released to an adequate extent at the point of intended use. This is not always straightforward if the substance is also to be sufficiently well encapsulated as to protect it prior to use.
It is an object of the present invention to provide ways of formulating active substances which can improve their stability to oxidation and hence overcome or at least mitigate the above described problems.